1. Field of the Invention
The present invention relates to an ink delivery system of a liquid electrophotographic color printer and an ink refilling method thereof, and more particularly, to an ink delivery system of a liquid electrophotographic color printer, which has a structure capable of refilling a plurality of ink storage tanks and a carrier storage tank which are installed in a main body of the printer with corresponding one of concentrated inks or a carrier by using a refill cartridge so as to supply liquid developers to developing units, and capable of recovering waste developer within a waste tank into an empty cartridge, and an ink refilling method thereof.
2. Description of the Related Art
In general, in a color printing device such as a color laser printer or a color copier, a latent electrostatic image formed on the surface of a photosensitive medium such as a photosensitive belt is developed with a liquid developer composed of a solid toner having a predetermined color and a liquid carrier functioning as a solvent, and the developed image is transferred to a paper.
A conventional liquid electrophotographic color printing device is provided with ink cartridges and a carrier cartridge which are installed to be replaceable at a main body of the printing device. The color printing device has an ink supplying structure in which concentrated inks and a carrier within the cartridges are supplied to respective developing units, and liquid developers required for the printing device are made by mixing the concentrated inks and the carrier. Here, the liquid developers are solutions made by mixing, in predetermined proportions, the concentrated inks composed of powder toners and are supplied from the ink cartridges and liquid carrier supplied from the carrier cartridge. The toners include pigments exhibiting colors of yellow, magenta, cyan, and black, respectively.
However, since the above cartridges supply the concentrated inks or the carrier contained therein to the developing unit via a predetermined passage and a pump, there is a disadvantage in that the passage between the cartridge and the developing unit is long. Also, although the cartridge has a characteristic of a consumable part, a functional part such as an agitator must be installed so that contents stored in the cartridge do not precipitate. Therefore, the conventional ink delivery system has a disadvantage in which the system is expensive.
Recently, in order to reduce the cost thereof, a printing device employs an ink delivery system in which tanks are provided in the vicinity of developing units. The functional parts such as an agitator can be omitted, and a refill cartridge is installed at the outside of a main body of a printer for supplying a carrier or inks to the respective tanks.
In a liquid developer circulation process of an ink delivery system, liquid developer which has been recovered at a corresponding circulation tank via a development gap of a developing unit and a drying/condensing unit is transferred from one developing unit to another, neighboring, developing unit by a circulating photosensitive medium. Such a developer mixing event in which the transferred developer is mixed with a peculiar developer in a circulation tank, i.e., cross contamination occurs. Therefore, when printing jobs are repeatedly performed, the purity of the liquid developers of the circulation tanks is not maintained within an allowable range due to the cross contamination, and the liquid developers stored in the circulation tanks become unusable waste developer. Under this situation, the waste developer must be discharged out of the circulation tank, and new inks and new carrier are refilled to the circulation tanks. Thus, a waste tank is installed at a printing device for recovering waste developer within the circulation tank.
In addition, although the waste developer in the waste tank can be recovered to a separate waste bottle installed at the printing device, a method of recovering waste developer by using an empty refill cartridge, corresponding to a tendency in which an ink delivery system employs a refill cartridge, is under consideration.